In recent years, in order to provide continuous service to customers at all times, technology for replicating data between storage systems has become extremely important, in such a manner that a data processing system can still provide services even if a problem has occurred in a first storage system. One example of technology for replicating the information stored in the first storage system to a second and a third storage system is that disclosed in the following patent reference.
U.S. Pat. No. 5,170,480 discloses technology whereby a first computer device connected to a first storage system transfers the data stored in the first storage system to a second computer device, via a communications link between the first computer device and the second computer device, and the second computer device transfers this data to a second storage system connected to the second computer device.